This year, the price of permits has fallen about 50 percent. Emissions allowances are now about 6 euros per ton—a four-year low, and about half what they were when the market began. Denmark, which will take over the presidency of the European Union in 2012, said the current carbon prices are “not sustainable” and vowed to help fix the problem.

The European Commission presented its long-awaited “Energy Roadmap 2050,” aiming to point the way to meet the European Union (EU) goal of cutting emissions at least 80 percent below 1990 levels by 2050.

A de-carbonized energy system could be cheaper than “business-as-usual,” although de-carbonization would require large up-front spending. The report also said natural gas will be a “critical” fuel during the transition.

The European Union moved earlier this year to expand its emissions trading scheme to include flights in and out of Europe, and now the European Court of Justice has backed that law despite protests from the U.S. and others. The new decision, which goes into effect Jan. 1, may trigger a trade war.

The U.S. Department of Justice is apparently working with law enforcement officials in Britain to investigate who leaked climate researchers’ e-mails.

In the U.K., police raided the home of one climate skeptic blogger and confiscated two of his computers.

Flipping the Switch on Incandescents

A ban on the sale of incandescent light bulbs of 100 watts or more in the U.S. is supposed to go into effect Jan. 1, but an emergency spending agreement in Congress removed funds from enforcement of the ban, at least until October 2012. Experts say the lack of enforcement will likely have little effect, since light bulb manufacturers have already retooled and moved on.